Bush is right, the bill does “authorize” the constrution of a new fence. But that doesn’t mean the bill pays for it. As the Washington Post reported earlier this month:

No sooner did Congress authorize construction of a 700-mile fence on the U.S.-Mexico border last week than lawmakers rushed to approve separate legislation that ensures it will never be built, at least not as advertised, according to Republican lawmakers and immigration experts.

… [S]hortly before recessing late Friday, the House and Senate gave the Bush administration leeway to distribute the money to a combination of projects — not just the physical barrier along the southern border. The funds may also be spent on roads, technology and “tactical infrastructure” to support the Department of Homeland Security’s preferred option of a “virtual fence.”

The “Secure Fence Act” has everything to do with motivating the right-wing base, and nothing to do with securing America’s borders or passing comprehensive immigration reform.